Camshaft



June 3, 1969 H. c. E. LATOUR GAMSHAFT Filed June 15, 1967 INVENT OR HENRI C'HARLE5 Em mo 1.47001? ATTORNEY United States Patent 3,447,395 t CAMSHAFT Henri Charles Edouard Latour, Geneva, Switzerland, as-

signor to Motosacoche S.A., Geneva, Switzerland, a corporation of Switzerland Filed June 15, 1967, Ser. No. 646,283 Claims priority, application Switzerland, Sept. 13, 1966,

13,228/66 Int. Cl. F16]: 53/02 US. Cl. 74-567 10 Claims ABSTRACT OF THE DISCLOSURE A camshaft of the tubular type rotating on a fixed axle especially suitable for an internal combustion engine includes separately made sintered cams. The cams are fixed in invariable positions relative to one another on the shaft by means such as slots and tenons on the terminal portions of their axes. The toothed driving wheel may be similarly made for attachment to the terminal portion of an end cam. The wheel may include a plastics overcasting on its teeth.

It is an object of the present invention to provide a camshaft which can be manufactured at less expense.

Other objects and advantages of the invention will emerge from the detailed description below.

According to the invention there is provideda camshaft of the tubular type burning around a fixed axle particularly for an internal combustion engine, wherein at least each cam is constituted by a separate part obtained by sintering, angular {fastening means of the cams one with respect to the other'being arranged at the ends of each part to enable anFinvariable assembly of the" cams one after the other.

In order that the invention may be more fully understood one embodiment of a camshaft according to the invention will now be described more fully, purely by way of illustrative example, with reference to the accompanying drawings in which:

FIG. 1 is a schematic view in elevation and in crosssection of one embodiment of a camshaft according to the invention; and

FIG. 2 is an end view of the camshaft of FIG. 1.

Referring to the drawing, this camshaft is of the tubular type turning around a fixed axle I mounted in an engine block or crank case, especially, for example, in an internal combustion engine. The camshaft shown comprises, in this example, only two cams 2 and 3 driven by a toothed wheel 4. Each of these cams 2 and 3 constitutes a separate part obtained by sintering. By such a process of manufacture, cams, even of complex profiles, are easily manufactured and at little expense. 7

To ensure that the angular position of the cams 2 and 3 one with respect to the other is ensured in invariable manner, special fastening means are provided. In the example shown, these fastening means comprise a group of slots 5 and of tenons 6 arranged at the ends of the members 2 and 3. The dimensions of the slots 5 and of the tenons 6 are selected so that their reciprocal engagement can only be effected in a particular angular position.

As is seen in FIG. 2, the upper slot 5 is narrower than the other slots and only one tenon of corresponding dimension, arranged on the other part, can be engaged in this narrow slot 5, which ensures a single possible angular position of one cam 2 with respect to the other cam. 3 As is shown in the drawings, not only each cam 2 and 3, etc. forms a separate part, but also the toothed driving wheel 4 of the camshaft is also obtained by sintering and forms itself a special member provided also with the group of slots 5 and tenons 6 which is adjacent to it. Preferably and to avoid costly manufacture of this driving wheel 4, the latter has an overcasting 7 of plastics material to form the contact surface of its teeth 8. As is shown in'FIG. 1, grooves 9 and 10 are channeled in the faces of the wheel 4 to ensure a good anchorage of the plastics overcasting material on the wheel 4.

Numerous modifications of the angular fastening means of the cams 2, 3, etc. and of the toothed wheel 4 with respect to the latter could be envisaged. In place of using groups of slots 5 and tenons 6, grooves could be arranged axially or possibly radially in the ends of the parts 2, 3, 4.

Angular fastening means for the different parts 2, 3, 4 are machined along the respective sides ensuring a force fit of the parts 2, 3, 4 one in the other, so as to avoid all angular play between these parts. Once the different parts 2, 3, 4 are engaged one in the other, the total length of the camshaft is adjusted by turning of one of the ends of the latter.

It is understood without further description from the foregoing that such a method of manufacture of camshafts enables the cost price of the latter to be substantially reduced, being given the great rapidity of making each cam 2, 3, etc. itself, by sintering. Moreover, the overmoulding of plastics material 7 to form the contact surface of the toothing 8 facilitates also the provision of such an inexpensive denture of light weight, precise and silent. The teeth 11 in sintered material constitutes an additional reinforcement and anchorage for the teeth 8 of plastics material. The coefficient of expansion of the plastics material would not permit construction of the wheel 4 entirely of plastics material since the temperature in the crank case of the motor can vary about C.

Having particularly described the invention, it is to be understood that it is not to be considered limited to the details herein set forth but that various modifications and changes of the embodiment described will occur to those skilled in the art and these are to be regarded as within the scope of the invention as defined by the appended claims.

I claim:

1. A camshaft of the tubular type rotatable around a fixed axle particularly for use in an internal combustion engine, wherein at least each cam comprises a separate sintered part, angular fastening means connecting the cams one with respect to the other and arranged at the ends of each part to provide an invariable and inseparable assembly of the cams one after the other.

2. A camshaft according to claim 1, wherein the fastening means comprises a group of slots and tenons designed to be engaged one in the other, the dimensions of the slot and tenons being selected so that their reciprocal engagement can only be effected in a particular angular position.

3. A camshaft according to claim 1, wherein the fastening means comprises channels arranged in the ends of each part having a cam.

4. A camshaft according to claim 1, including a toothed driving wheel connected by angular fastening means against the cams.

5. A camshaft according to claim 4, wherein the toothed driving wheel is also sintered.

6. A camshaft according to claim 1, including a toothed driving wheel having an overcasting of plastic material to form the contact surface of its teeth.

7. A camshaft according to claim 5, wherein said toothed driving wheel has an overcasting of plastic material to form the contact surface of its teeth.

'8. A camshaft according to claim 6, wherein the toothed driving Wheel has channeled in its faces, grooves providing firm anchorage for said overcasting.

9. A camshaft according to claim 7, wherein said toothed driving wheel has channeled in its faces, grooves providing firm anchorage of said overcasting.

10. A camshaft according to claim 1, wherein said angular fastening means comprise grooves.

References Cited UNITED STATES PATENTS 10/1924 Luitwieler 74-567 6/ 1949 Essl 74-568 8/1965 Dew 74443 XR FRED C. MATTERN, JR. Primary Examiner.

F. D. SHOEMAKER, Assistant Examiner.

US. Cl. X.R. 

